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    <title>portr3d</title>
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    <center>Scilab Function</center>
    <div align="right">Last update : April 1993</div>
    <p>
      <b>portr3d</b> -  3 dimensional phase portrait.  </p>
    <h3>
      <font color="blue">Calling Sequence</font>
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    <dl>
      <dd>
        <tt>[]=portr3d(f,[odem,xdim,npts,pinit])  </tt>
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      <font color="blue">Parameters</font>
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    <ul>
      <li>
        <tt>
          <b>f</b>
        </tt>: a Scilab external which gives the field of the dynamical system. Hence  it can be a macro name which computes the field at time t and point x [y]=f(t,x,[u]) or a list list(f1,u1) where f1 is a macro of type [y]=f1(t,x,u) or a character string</li>
      <li>
        <tt>
          <b>.I rest</b>
        </tt>: The other parameters are optional. If omitted they will be asked interactively<ul>
          <li>
            <tt>
              <b>odem</b>
            </tt>: gives the integration method to use. The value "default" can be used,  otherwise see ode for a complete set of possibilities</li>
          <li>
            <tt>
              <b>npts</b>
            </tt>:  a vector of size (2,10) [number-of-points,step] gives the step for integration  and the number of requested points. The solution will be calculated and drawn  for time=0:step:(step*[number-of-points])</li>
          <li>
            <tt>
              <b>xdim</b>
            </tt>: [xmin,xmax,ymin,ymax,zmin,zmax] the boundaries of the graphic frame.</li>
          <li>
            <tt>
              <b>pinit</b>
            </tt>: initial values for integration. A set of initial points can be given in a matrix<pre>

      pinit = [x0(1), x1(1),...., xn(1)
               x0(2), x1(2),...., xn(2)
               x0(3), x1(3),...., xn(3)].
   
                </pre>
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    <h3>
      <font color="blue">Description</font>
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    <p>
    Interactive integration and display of a 3 dimensional phase portrait
    of a dynamical system  dx/dt=f(t,x,[u]) (where u is an optional parameter )</p>
    <h3>
      <font color="blue">See Also</font>
    </h3>
    <p>
      <a href="../nonlinear/ode.htm">
        <tt>
          <b>ode</b>
        </tt>
      </a>,&nbsp;&nbsp;</p>
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